Burner Arrangement

ABSTRACT

The invention relates to a burner arrangement comprising a burner plate ( 1 ) having a multiplicity of apertures ( 2 ) and a monitoring device for monitoring the formation of a combustion zone ( 3 ) extending from the burner plate ( 1 ), wherein the monitoring device comprises a cathode ( 5 ) provided on a flame-side top ( 4 ) of the burner plate ( 1 ) and an anode ( 7 ) arranged in the region of the combustion zone ( 3 ). To improve the thermal stability and thus the durability, provision is made according to the invention for the burner plate ( 1 ) to be made of a non-metallic material and for the cathode ( 5 ) to be arranged as a separately designed component in the region of the top ( 4 ) of the burner plate ( 1 ).

The invention relates to a burner arrangement as defined in the preambleof claim 1.

Such a burner arrangement is generally known in accordance with thestate of technology. In particular, gas burners are equipped with anozzle or burner plate made of metal. During operation of the gasburner, a gas flowing through the nozzles is burnt. In this connection,flames extend from a top side of the burner plate. During operation, itcan happen, among other things, that the flames are extinguished by agust of wind, for example. In this case, gas would escape through thenozzles. In a closed room, for example, this can create an explosivemixture of gas and air. To avoid this, a monitoring unit is provided onthe burner plate to monitor the extinguishment of the flames extendingfrom the burner plate. In the monitoring unit, the metallic burner plateserves as the cathode. An anode is provided above the cathode in thearea of the flames. The extinguishment of a flame can be detected basedon a significant change in the electrical conductivity between thecathode and the anode and, as a result of this, a safety shutoff valveinstalled in a gas feeder line can be closed. Such gas burners whichburn the gas by creating an open flame do not make optimal combustionpossible, among other things.

From DE 43 22 109 A1 a so-called gas pore burner is known. In thisconnection, the gas is burned in a volume burner element made of porousceramic. The suggested gas pore burner makes possible particularly cleancombustion. Due to the provision of a volume burner element, anundesirable breakdown of the combustion reaction will almost never occurduring operation.

However, also with such a gas pore burner the undesirable escape ofcombustible gas is still possible, for example, due to a defectiveignition unit.

The object of the invention is to eliminate the disadvantages as per thestate of technology. In particular, a burner arrangement is to bespecified which makes low-pollution combustion possible and, at the sametime, the quick and reliable detection of the undesired escape ofunburnt fuel.

This object is solved by the features of claim 1. Useful embodiments ofthe invention result from the features of claims 2 to 12.

According to the provisions of the invention, it is provided that theburner plate is made from a non-metallic material and the cathode islocated as a separately formed component in the area of the top side ofthe burner plate.

Due to the use of a non-metallic material, a ceramic material forexample, to make the burner plate, the temperature resistance and thusthe durability of such a formed burner arrangement is improved. Theprovision of a cathode designed as a separate component makes possiblethe creation of the monitoring unit to monitor the formation of acombustion zone extending from the burner plate. The suggested burnerarrangement makes possible quick and reliable detection of theextinguishment of a flame, a faulty ignition or similar. The suggestedburner arrangement is suitable for the implementation of both surfaceand volume burners. Such burners make particularly clean fuel combustionpossible. The term “fuel” is understood to mean in particular gaseousfuels, for example combustible gases, vaporized liquid fuels, forexample mixtures of vaporized oil and air, alcohol/air mixtures andsimilar.

According to an advantageous embodiment, it is provided that a volumeburner body with a combustion-enabling, communicating pore area islocated opposite the top side. The provision of such a volume burnerbody makes possible a simple and inexpensive way to make a volumeburner. In this case, the combustion of the fuel occurs essentiallywithin the volume burner body. In this connection, a slit with aspecified width can be provided between the top side and a bottom sideof the volume burner body. The width of the slit is usefully 0.5 to 15mm, preferably 1 to 5 mm. The provision of the suggested slit simplifiesignition.

According to a further advantageous embodiment, the volume burner bodyand/or the burner plate is/are made of a ceramic material. In thisconnection, this can be porous ceramic, a perforated plate, a ceramicfoam or similar.

According to a useful embodiment, the cathode is located in the slit. Itcan lie on the top side, for example. But it is considered asparticularly advantageous when the cathode is contained in a recesswhich opens towards the top side of the burner plate. In this case, anundesirable strong heating up of the cathode during the operation of theburner arrangement is avoided. This makes possible a particularlyprecise detection of a malfunction.

It is useful that at least some of the breakthroughs provided in theburner plate open in the recess. Due to this, the cathode contained inthe recess is surrounded by still unburnt gas and thus cooled.

The recess is preferably designed deep enough so that the cathode can becompletely contained in it. In other words, the cathode does notprotrude out of the recess over the top side, in particular, not in thearea of the combustion zone.

According to a further embodiment, it is provided that the cathodeextends from the recess to a further bottom side of the burner plateopposite the top side. This makes possible a simple way to conduct offthe heat from the cathode to the opposite further bottom side which iscool.

According to a further embodiment, it is possible that the cathode iscontained in a recess which opens towards the bottom side of the volumeburner body. Besides this, it is also conceivable that to some extentthe cathode is partially contained in a [lacuna] on the top side of theburner plate as well as in a [lacuna] on the bottom side of the volumeburner body.

According to a further embodiment, it is provided that the recess isformed corresponding to the shape of the cathode. This provides a simpleand inexpensive way to prevent undesired strong heating up of thecathode.

The cathode can be formed from a perforated plate or, preferably aspiral or meandering-shaped, bent wire. It is usefully made of atemperature-resistant metal.

The suggested burner arrangement is usefully used with gas burners inparticular.

Examples will now be used to describe the invention in more detail basedon the drawings. The figures are listed below:

FIG. 1 A perspective view of a first burner arrangement,

FIG. 2 A sectional view as per FIG. 1,

FIG. 3 A perspective view of a second burner arrangement,

FIG. 4 A detail view of area A in FIG. 3,

FIG. 5 A perspective view of a first cathode,

FIG. 6 A perspective view of a second cathode,

FIG. 7 A perspective view of a third cathode and

FIG. 8 A perspective view of a fourth cathode.

FIG. 1 and 2 show views of a first burner arrangement. The burner is asurface burner. A burner plate 1 made of a ceramic material, for exampleAl₂O₃, ZrO₂ or similar, has the form of a cylindrical disk. Burner plate1 is provided with a plurality of axially running breakthroughs 2 toconduct a gaseous fuel, for example. Reference designator 3 denotesflames extending from a top side 4 of the burner plate 1. A diameter ofthe breakthroughs 2 is selected in such a manner that the spread of theflames 3, in other words the formation of a flame 3 within thebreakthroughs 2, is impossible. A cathode 5 made of atemperature-resistant metal is contained in a correspondingly formedrecess 6 which opens towards the top side 4. The depth of the recess 6is such that the recess can completely hold the cathode 5 which isdesigned, for example, in the shape of a bent wire. In other words, thecathode 5 does not protrude over the top side 4. The breakthroughs 2 canextend into the recess 6. The recess 6 can be made either by milling,grinding or similar after the firing of the ceramic which forms theburner plate 1. But preferably the recess 6 will already be made beforethe firing of the burner plate 1 by appropriate shaping or processing ofthe green body.

Reference designator 7 denotes an anode which protrudes into the area ofthe flames 3 in the approximate opposite arrangement to cathode 5.

As FIG. 1 particularly shows, the ends 5 a of the cathode 5 are ledthrough and out of the burner plate 1 via a bottom side of burner plate8.

FIG. 3 and 4 show a second burner arrangement. In this connection, avolume burner element 9 made in the shape of a cylindrical disk isprovided above the top side 4 of the burner plate 1. A slit 11 formedbetween the top side 4 and a volume burner bottom side 10 has a width inthe range of 1 to 5 mm.

The volume burner element 9 is usefully made of a porous material, forexample a porous ceramic, a ceramic foam, metal braiding or similar. Thevolume burner element 9 has a further breakthrough 12 through which theanode 7 is led up to the vicinity of the top side 4 of the burner plate1.

The function of the burner arrangements is stated below:

Gas flows through the breakthroughs 2 in the burner plate 1. The gas isignited with a ignition device (not shown here). Because of this, theflames 3 extend from the top side 4 to the burner plate 1. Due to theformation of the flames 3, a significant change in the electricalconductivity is measured between the cathode 5 and the anode 7 via ameasuring device (not shown here). This change shows the existence ofthe flames 3. If the flames 3 do not occur, due to a faulty ignition orgust of wind for example, or are extinguished, this is detected by thelack of increased conductivity between cathode 5 and anode 7. Forexample, a safety shutoff valve installed in a gas feeder line can beautomatically closed.

To obtain as reliable conductivity measured values as possible, it hasproven useful to maintain the cathode 5 within a specified temperaturerange. For this purpose, the cathode 5 is placed in the recess 6 whichopens towards the top side 4 of the burner plate 1. As particularlyshown in FIGS. 1 and 2, the flames 3 extend first from the top side 4 ofthe burner plate 1. In other words, the cathode 5 is not located withinthe flames 3. Apart from this, the cathode 5 can be surrounded with gasthrough the breakthroughs 2 extending into the recess 6 and thus becooled or maintained within a specified temperature range. For furtherthermal stabilization of the cathode 5, it is useful to lead out itsends 5 a through the bottom side of the burner plate 8. With this, heattransferred to the cathode 5 in the area of the top side 4 can be guidedto a cooler area on the bottom side of the burner plate 8. The suggestedarrangement of cathode 5 makes possible safe and reliable detection ofthe existence or non-existence of a flame 3.

FIG. 5 to 8 show possible embodiments of the cathode 5. In FIG. 5 to 7the cathode 5 is made from a bent wire. It has at least one end 5 a eachfor leading through up to the bottom side of the burner plate 8. As FIG.5 to 7 show, the wire can be bent either meandering-shaped or also likea spiral.

The cathode 5 shown in FIG. 8 consists of a perforated plate with a heatdissipating and connection element 13 extending therefrom.

REFERENCE DESIGNATION LIST

1 Burner plate

2 Breakthrough

3 Flame

4 Top side

5 Cathode

5 a End of the cathode

6 Recess

7 Anode

8 Bottom side of burner plate

9 Volume burner element

10 Bottom side of volume burner element

11 Slit

12 Further breakthrough

13 Heat dissipating and connection element

1. Burner arrangement with a burner plate (1) having a plurality ofbreakthroughs (2) and a monitoring unit to monitor the formation of acombustion zone (3) extending from the burner plate (1), wherein themonitoring unit comprises a cathode (5) on a top side (4) of the burnerplate (1) pointing towards the combustion zone (3) and an anode (7)extending into the area of the combustion zone, characterized in thatthe burner plate (1) is made of a non-metallic material and the cathode(5) is located as a separately formed component in the area of the topside (4) of the burner plate (1).
 2. Burner arrangement as defined inclaim 1, wherein a volume burner body (9) with a combustion-enabling,communicating porous space is located opposite the top side (4). 3.Burner arrangement as defined in claim 1, wherein a slit (11) of aspecified width is provided between the top side (4) and a bottom side(10) of the volume burner body (9).
 4. Burner arrangement as defined inclaim 1, wherein the volume burner body (9) and/or the burner plate (1)is/are made of a ceramic material.
 5. Burner arrangement as defined inclaim 1, wherein the cathode (5) is located in the slit (11).
 6. Burnerarrangement as defined in claim 1, wherein the cathode (5) is containedin a recess (6) opening towards the top side (4) of the burner plate(1).
 7. Burner arrangement as defined in claim 1, wherein at least someof the breakthroughs (2) provided in the burner plate (1) open in therecess (6).
 8. Burner arrangement as defined in claim 1, wherein thecathode (5) extends from the recess (6) into a further bottom side (8)of the burner plate (1) opposite the top side (4).
 9. Burner arrangementas defined in claim 1, wherein the cathode (5) is contained in a recess(6) which opens towards the bottom side (10) of the volume burner body(9).
 10. Burner arrangement as defined in claim 1, wherein the recess(6) is formed corresponding to the form of the cathode (5).
 11. Burnerarrangement as defined in claim 1, wherein the cathode (5) is formedfrom a perforated plate or preferably a spiral or meandering-shapedwire.
 12. Burner arrangement as defined in claim 1, wherein the burnerarrangement is part of a gas burner.